Automatic machine for checking the weight of open cans containing liquid or semiliquid substances



March 12, 1968 L. PUOTI 3,372,804

AUTOMATIC MACHINE FOR CHECKING THE WEIGHT OF OPEN CANS CONTAINING LIQUID OR SEMILIQUID SUBSTANCES Filed Nov. 19, 1965 I 2 Sheets-Sheet 1 INVENTOR. "L/ uoiL',

hwda g iu ATTORNEL-QS March 12, 1968- L. PUOTI 3,372,804

AUTOMATIC MACHINE FOR CHECKING THE WEIGHT OF OPEN CANS CONTAINING LIQUID OR SEMILIQUID SUBSTANCES Filed Nov. 19 1965 2 Sheets-Sheet 2 I INVENTOR. L Pu 011' BYOLMM United States Patent C) 3,372,804 AUTOMATIC MACHINE FOR CHECKENG THE WEIGHT OF OPEN CANS CONTAINING LIQ- UID OR SEMILIQUID SUBSTANCES Lionello Puoti, Via Confalone 7, Naples, Italy Filed Nov. 19, 1965, Ser. No. 508,777 Claims priority, application Italy, Sept. 30, 1965, 21,533/65 6 Claims. (Cl. 209-74) ABSTRACT OF THE DISCLOSURE A machine for checking the weight of open filled cans includes scales for individual cans mounted upon a movable conveyor, the cans being transferred from another movable conveyor individually upon the scales by a deviator. Another deviator shifts cans having the proper weight from the scales to a third conveyor, while cans of insufficient weight are moved by a third deviator to a fourth conveyor.

A number of machines are commonly used in commercial canning for checking the precise weight of the filled cans in order to prevent any customers complaints due to the weight of the content being less than that stated.

Such machines, with the exception of a known type which is electronically operated and which among other drawbacks is extensive and not much reliable suifer from the disadvantage of operating with already closed cans because otherwise an intolerable loss of the can content would occur due to the shocks imparted to the can by the machine.

Such a drawback is aggravated due to the fact that no addition to the content of the insufficiently filled cans, for bringing their weight up to the desired value, is any more possible. As a consequence, only two alternatives are offered to the manufacturers, that is to sell the insufficiently filled cans at a lower price after correcting the stated weight, or open them again to recover the content, in which case the can i no more usuable if it has been seamed.

The machine which is the object of the present invention while making use of devices which are purely mechanical and inexpensive does not have the above disadvantage in as much as it permits the selection of the still open cans, without any product being spilled from the can during the selecting operation, an addition of product to the insufiiciently filled cans being still possible.

This result is achieved according to the invention by arranging the different parts of the machine in such a way that the cans which advance along the machine are not subjected to accelerations strong enough to cause the surface of the liquid in the can to become s inclined as to reach the can lip and that the cans are never subjected to forces capable of overturning them.

How these conditions are met will become clear from the following briefs description of the machine. The cans to be selected are fed to the machine by means of a conveying belt; from this belt they are transferred to a plurality of scales which are carried on an endless chain or weighing conveyor.

This conveyor is so positioned that its upper length runs parallel and close to the upper length of the conveying belt and that the top surface of the scale pans carried by it is at the same level as the top surface of the conveying belt, both the scale pans and the conveying belt top surface being moved in the same direction, and at the same constant speed; the cans are transferred from the conveying belt to the weighing conveyor by means of a deviator that is a rail suitably bent in a horizontal plane to form a profile along which the cans are led to slide and consequently to be forced sidewise. The deviator profile P (see FIG. 9) will be designed according to the shape of the cans in plan view in a way that in any case the trajectory of the center of gravity of each can is formed with two branches of a second order parabola the first branch L-M pertaining to a parabola a of which the x axis is perpendicular to the straight line trajectory of the centers of gravity of the cans which travel along the feeding belt and the apex is lying on the same trajectory and the second branch MN pertaining to a parabola b of which the axis is parallel to the axis of the parabola of the first branch and the apex is lying on the straight trajectory of the cans which are carried forwards on the weighing conveyor (see FIG. 9). Both the aforesaid parabolas have the same parameters and the two branches of them being used in the deviator have a common tangent line in the point M where they join together.

Due to such form of the deviator the cans being transferred from the feeding belt to the scales, in addition to the advancing motion, which is a uniform motion in the same direction as the feeding belt and the scales, are subjected to a crosswise motion which, along the first branch of the deviator is uniformly accelerated and along the second branch is uniformly decelerated. The acceleration and the deceleration will depend upon the advancing speed of the cans and upon the form of the parabola which has been chosen, however within a certain limit of the advancing speed said acceleration and deceleration can always be kept lower than the value which is liable to cause the spilling of the liquid from the cans, this being achieved after choosing a certain parabola, by properly changing the parameters of the same parabola.

Deviators of similar kind are used for switching the cans from the scales to the conveying belts after the cans selection thus the first of the two above mentioned conditions is fulfilled. To fulfill the second condition that is of not overturning the cans, the deviators are placed at a level a little higher than the can bottom.

The detailed description of the machine will follow and it will be better understood when referring to the attached drawings of a preferred embodiment of the invention which is illustrated only as an example of it.

in the drawings:

FIG. 1 is a diagrammatic plan view of the machine.

FIG. 2 is a side view of the same.

BIG. 3 is a -oross-section along line Ill-III of FIG. 1.

FIG. 4 shows one of the scales as viewed while advancing towards the observer.

FIG. 5 shows one of the scales as viewed from the right side of FIG. 4-.

FIG. 6 shows a scale at a little distance in front of rod 20, the scale projection being midway between end positions A and B.

'FIG. 7 is a plan view of rod 20 and piece 21 in their rest position.

'FIG. 8 shows the deviators is based.

The machine comprises: three conveying belts 1, 2 and 3 of a known type which move in the direction of the arrows, all being moved at the same speed by means of a motor and drives not shown; a plurality of scales 4 which are carried on an endless chain conveyor which hereinafter will be referred to as the weighing conveyor; the endless chain being wound around sprockets 6, the peripheral speed of the conveyor, that is the speed of the scales, being the same as that of the conveying belts.

FIGS. 4 and 5 are two side views of a scale and in FIG. 5 the end positions of the vertical travel of a scale pan are shown. As shown in FIG. 5 a scale comprises, in a preferred embodiment, a weight 7 which through a parabolas on which the form of lever 8 moves the scale pan 9, the latter being kept always parallel to itself by means of link 10.

Scale pan 9, one side of which has a side turned upward to form an edge, is connected to the linkage consisting of lever 8 and link 10 by means of bracket 11.

Plate 12 connects the scale mechanism to the endless chain 5 through brackets '13 which are attached thereto.

The scale travel is limited upwards by stop tab 14 and downwards by bracket 11 abutting against plate 12.

The operation of the machine is as follows. Cans 15 to be weighed are fed to the machine in a single row and close one to the other on belt 1.

Along their travel they engage deviator 16 which is attached to the machine frame 37; due to the deviator profile the cans are displaced crosswise and transferred to scales 4 of the weighing conveyors of which the forward speed and direction are the same as those of the conveying belt 1 and thereafter they lose contact with the deviator.

The scale pans, as shown in FIGURES 4 and 5 have one side bent upwards for the purpose of separating two adjacent cans one from the other enough for ensuring the unobstructed and proper operation of the scales.

The scales during this step of operation have their pans at the level of belt 1 and because they are unloaded their position is at A ('FIG. 5) due to the action of weight 7 and of stop tab 14.

While moving forwards those scales which receive cans having the proper weight or more will sink and reach the position -B, while those which receive cans of lower weight will remain at position A. As a consequence, the properly filled cans will engage deviator 17 which will shift them to conveying belt 2 which runs at the same level as 'the scale pans when these are at position B, while the same deviator will not be engaged by cans weighing less than the required weight and will pass freely between the scale pan 9 and the scale mechanism through a space which is left free due to the folded shape of bracket 11 as shown by FIG. 3.

The low Weight cans in their further travel will engage deviator 18 which is also attached to the machine frame 37 and is placed at a higher level than the scale pan when the latter is at position A, which deviator will transfer them to conveying belt 3, the upper surface of the latter being at the same level as the upper surface of belt 1. Thus the belt 2 will carry all the cans of insufficient weight.

However, it could happen that while the cans are transterred from the scale to conveying belt 2, the scales being relieved of a part of the can weight, because this is gradually transferred onto belt 2, would start suddenly their upward movement towards position A. Due to this movement they could interfere with the subsequent deviator 18. To prevent this, a rod is provided for engaging a flat projection 19 of the scale to keep the latter at the depressed position B until the scale has passed the beginning of deviator 18.

Rod 20, which extends from station S to station T, that is from a station midway between deviator 16 and deviator 17 to a station just before the front end of deviator 18, has a rectangular cross-section and a wedgelike end which faces the incoming scales, said wedgelike end being formed by the upper side of the rod which is horizontal for the whole length thereof while the lower side is inclined for a portion thereof and subsequently becomes horizontal that is parallel to the upper side.

A portion of the Wedgelike end of rod 20 is cut off to form a step in plan view; this is for leaving a space free for a swinging device consisting of a flat metal piece ,21 which is shaped like a wedge with the point facing the incoming scales. Piece 21 is supported by a lever 22 rotatably mounted on a pin which is attached to the rod or to any point of the machine frame. Lever 22 is resiliently connected to the machine frame by means 4 of spring 24 and abuts against peg 25 which also is attached to the machine frame.

The purpose of said rod and swinging device is as follows: when the can Weight is just a little greater than the calibration weight of the scale, the downward motion of the scale pan is very slow and because the travel from position A to position B of the scale pan cannot be less than a certain amount in order to permit the light cans to pass above and the heavy ones to pass below deviator 17, the time for the heavy cans to reach position B could be too long and the corresponding horizontal distance travelled by the cans in the meanwhile would require an excessive length of the machine between the station where the can is transferred on the scale and the front end of deviator 17. This inconvenience is overcome by means of projection 19 of the scale and to rod 20 with its wedgelike point. In fact, when a scale reaches the rod point while the scale projection is still at position A or slightly below, any further downwards movement of the scale is stopped by rod 20 but if a scale reaches the rod point while the scale projection is at a position between A and B but lower than the rod point, that is if the scale is on its way downwards or has already reached position B, the scale projection will engage the lower inclined surface of rod 20 and sliding along the latter, will be compelled to reach rapidly position B at the end of the inclined portion of rod 20. It is obvious that the weight of those cans that reach the rod point is greater than the sufficient weight as previously determined, because otherwise their downward movement would not even begin.

However it could happen that some scales reach the rod point when their projection is exactly at the same level as the rod point. In this case the device consisting of piece 21 and lever 22 would intervene, as shown in FIGS. 6 and 7.

Piece 21 supported by lever 22 can swing through an angle about pin 23 and is maintained at position F by means of spring 24 against a stop peg 25. When lever 22 is at position F, piece 21 is in a more advanced position than the foremost end of rod 20 and its position in plan view is as shown in FIG. 7, that is laterally with respect to the longitudinal axis of rod 20. Spring 24 is so adjusted that usually lever 22 is maintained at position F and therefore piece 21 is maintained in an advanced position with respect to rod 20 even if a scale projection 19 which reaches piece 21 slides along the upper or the lower surface thereof. However as often as a scale projection reaches piece 21 exactly at the same level thereof, the projection engages the piece front edge and, overcoming the action of spring 24, forces piece 21 to rotate about pin 23; the piece edge is therefore moved along an arc of a circle centered at 23; due to the frictional action between the piece edge and projection 19 and to the small resistance encountered by the scale in its downward movement, projection 19 is driven so as to follow pieces 21 along said are. The result is that when the scale projection reaches the foremost end of rod 20, its level is lower than the rod edge, so that said projection does not collide with the rod edge but can slide along the lower side of rod 20 and follow the same way as the scales which reach the piece 21 at position B. Lever 23 is then restored to position F with piece 21 ready to receive another scale projection reaching it while at position D.

This avoids any damage to the machine due to jamming between projection 19 and rod 20.

It should be understood that while an embodiment of the invention has been described as a non limitative example thereof, a number of changes and modifications can be introduced in said embodiment which will be still within the scope of the attached claims.

For instance the conveying belts of the machine could have a different arrangement and direction with respect to that shown in the drawing, in which case the profile of deviators 16, 17 and 18 would be modified in order to limit the acceleration or deceleration of the cans at the required value. When the cans contain a very viscous or thick liquid a strictly constant acceleration during the transfer motion of the cans from the conveying belts to the scales and vice-versa is no more essential but the acceleration must be limited also in this case to a value lower than that required for preventing any spilling liquid; similarly the arrangement of the machine could be such that when receiving the cans to be weighed, the scales position will be at position B instead of position A and that the sales, after being loaded with the cans, move upwards instead of downwards, this being achievable by means of a guide acting on weight 7 or on projection 19.

What I claim is:

1. In a plant for canning any loose, liquid or semiliquid substance an apparatus for selecting the filled cans with their top side still open according to their weight and separating those which weigh less than a predetermined weight from the remainder, said cans being fed to the selecting device by means of a first conveying belt, a second conveying belt being provided for leading away from the selecting apparatus the cans weighing more than said predetermined weight and a third conveying belt provided for leading away from the selecting apparatus the cans which weigh less than said predetermined weight, which apparatus comprises a first level deviating rail which is mounted in a fixed position at a small distance above the upper surface of said first conveying belt, said rail extending slantingly across the latter surface, a weighing conveyor which is made of two parallel endless chains wound around two pairs of sprockets, and running horizontally for a length, each link of one of said chains being connected to the corresponding link of the other chain by means of a bracket which supports a scale consisting of a weight, a parallel linkage and a scale pan, the outermost periphery of said weighing conveyor being formed with a plurality of scale pans pertaining to the plurality of the chain links; said scale being subjected to a downward movement as often as a can weighing more than the predetermined weight is placed on said scale pan; the weighing conveyor being located along one side of said first conveying belt with the scale pans at the same level of the upper surface of said conveying belt; a second level deviating rail which is mounted in a fixed position above and close to the upper surface of said second conveying belt the latter surface being placed at the same level as the lowermost level reached by the scale pan during said downward movement under the weight of the can; which second rail extends slantingly across the upper surface of said Weighing conveyor; a third level rail which is mounted in a fixed position at the same level as the first rail; that is just above the level of the upper surface of said third conveying belt said third rail extending across the latter surface whereby the cans which travel along said rails in the order above described are moved from said weighing conveyor to the second conveying belt when their weight is equal or greater than the predetermined weight and to the third conveying belt when their weight is less than the predetermined weight.

2. Apparatus as per claim 1 in which the profile of said first, second and third deviating rails along which the cans are led to be moved sidewise from the conveying belts to the weighing conveyor and vice-versa, is the envelope of the different positions of the horizontal projection of a can body when its center of gravity is moved on a horizontal plane along a curve formed with two branches of parabolas of which the first pertains to a first parabola having its x axis perpendicular to the rectilinear trajectory of the center of gravity when it reaches the deviating rail and its apex on the same trajectory while the second pertains to a second parabola of which the equation parameters are the same as for the first parabola and the x axis is perpendicular to the rectilinear trajectory of the center of gravity when it is moved away from the deviating rail and the apex lies on the latter rectilinear trajectory;

the two branches of the parabola joining in at a point wherein they have a tangent in common, thereby when the cans are led to slide along the deviating rail, their crosswise movement is uniformly accelerated along the first branch and uniformly decelerated along the second branch, this being the condition to be fulfilled for obtaining the transfer of the cans from the conveying belts to the weighing conveyor and vice-versa within the shortest possible length of the machine without imparting to the can acceleration and deceleration greater than the predetermined value.

3. An apparatus as per claim 1 in which the scales are moved at a constant and rectilinear speed along that section of the weighing conveyor partially or totally loaded with the cans.

4. An apparatus as per claim 1 in which the deviating rails engage the can side near the can bottom, whereby the cans are not exposed to the danger of being overturned when they are engaged by said deviating rails.

5. An apparatus as per claim 1 in which the pan of each scale is connected to the linkage thereunder by means of a bracket which is bent to form a horizontal slot through which the second deviator can pass between the scale pan and the scale linkage without interfering with the scale structure when, due to the insufiicient weight of the can, the travelling scale is at the uppermost position.

6. An apparatus as per claim 1 which is provided with a rod extending lengthwise of the weighing conveyor from a point midway between said first deviating rail and the second deviating rail to a point just before the front end of said second deviator which rod has a rectangular cross section and is tapered for a portion thereof pointing toward the incoming scales, the upper side of said rod being horizonal for the whole length of it and the lower side being sloped for the length of said portion of it and subsequently becoming horizontal, that is parallel to the upper side of said rod, each scale being provided with a lateral projection for engaging the upper side of said rod when the scale pan reaches said rod while being at a position higher than the rod pointed end, whereby any downward movement of these scales is stopped and for engaging the lower side of the same rod when the scale pan reaching the rod is at a position lower than the rod pointed end whereby these scale pans are forced to speed up their downward movement until they reach the lowermost end of their vertical travel; the tapered end of said rod being cut off to form a lateral step in plan view in order to leave a space free for receiving a device consisting of a flat wedgelike piece with its point facing the incoming scales, said piece being supported by a lever rotatably mounted on a horizontal pin perpendicular to the scales travel and above said piece, which lever being kept in a vertical position by a spring and a peg against which the lever abuts under the spring action; the point of said piece being at the same level of the rod point when said lever and piece are at rest and moving along an arc of a circle when displaced from its rest position due to the force applied to it by a scale projection colliding with the piece point, whereby any scale pan which reaches said device at the same level of the piece point, that is at the same level of the rod point is compelled to move downwards due to the frictional action of the piece point on the scale projection and thereafter to slide along the lower surface of said rod.

References Cited ALLEN N. KNOWLES, Primary Examiner. M. HENSON WOOD, JR., Examiner. 

